Preparation of lead borate



Sept., 10,1935. G. E. slEvl-:R'r

` PREPARATION OF LEAD BORATE Filed July 18, 1953 A [N VE N TOR z//Lfo ESJEVEJQT A T T ORNE Y Patented Sept. 10, 1935 UNITED sTATfEs PATENT oFFIcE PREPARATION OF LEAD BORATE Guilio E. 4Sievert, South Gate, Calif.

Application July 18, 1933, Serial No. 680,987

2 Claims. A (Cl. 204--9) This invention relates tothe preparation of lead borate and its use in glazes for ceramicA coatings.

In the glazing of pottery it is necessary to apply a glazing material to the surface of the article of pottery and to thereafter heat the article until a suitable glaze has been produced.

In common practice certain ingredients o-f glazing material are usually formed in what is known to the trade as a ritwhich is fired and must then be ground to a desired degree of neness before it is applied to the article. In practice it is found that in some instances subsequent iiring of the pottery causes cracks to form in the glaze material which sometimes results in causing the glaze to peel away from the body before fusion occurs.

It is the principal object of the present invention to provide a product, a process of its produc- 0 tion, and use upon articles of pottery, which prodindicates an electrolytic precipitation cell having cathode plates I'I therein, and one or more anode plates I2. Diaphragms I3 and I4 are interposed between the cathode and anode plates and are of such a character as to permit ionizaytion lcurrents to ow while retarding the mingling of the electrolyte solution from the area occupied by the anode with the lsolution in the area occupied by the cathode. 'Ihe anode is formed of lead. The cathodes are preferably formed of steel or other metal which will not react to the materials in solution. Acase I5 is provided for the precipitation cell I0, and is here shown as formed with two draw off pipes II and I8 through which electrolyte solution may be drawn through a -pipe I9 to a catholyte tank 20. returned to the cathode portion of the cell I5 through a pipe 2l and by suitable means such as pump 22. The catholyte solution has a boric acide content. The solution has been made by lthe catholyte section of tank 20.

The liquid within this tank may be dissolving boric acid in relatively small quantities of hot water before being added to the solution of sodium acetate or an equivalent chemical element. It is preferable that the strength of the solution shall be of the order of a sat- 5 urated boric acid solution at 25C. The boric acid thus formed is added to a solution of sodium acetate. Such a solution, containing two ounces of sodium acetate to a gallon has been found to be suitable. The boric acid is introduced into l0 the sodium acetate solution while hot and until a saturated solution of boric acid is made.

It is desirable to maintain such a solution in This may be done by replenishing the boric acid solution with 15 Athe sodium acetate'solution of the strength pre- 4 ,the tank through a pipe 2'I and is conveyed to an anolyte storage tank 28. This anolyte is returned to the portion of the cell II) occurring between the diaphragms I3 and I4 through a pipe 28'. This may be accomplished by a pump 29.

The lead borate which is drawn through the pipe 26 is delivered to suitable washing and filtering equipment generally indicated at BUI. The liquid from this equipment is delivered into the anolyte tank 28 while the filter cage is drawn from the filtering equipment, dried and then placed in containers. The final product will be a high grade of lead borate which may then be used as a glazing material in pottery work.

The electrolytic cell I0 which is used may employ any desired direct current, but in practice it has been found that a current having voltage of from 31/2 to 6 volts, and an amperage in the order of 15 amperes per square foot of anode surface, nearness of the anodes to the cathodes, strength of solution and temperatures to obtain a satisfactory maximum precipitate of lead.

After the lead borate has been filtered and dried it is then ready for `use in a glaze formula designed for a particular purpose. A typical glaze formula for producing sanitary ware with a white glaze is set forth in percentages of raw materials 55 as follows:

Per cent Silica. 24.79 Lead borate 19.32 Ball clay 0.62 Calcined china clay 4.05 Raw china clay 1.41 Feldspar 21.25 Whiting 3.48 Zinc oxide 7.37 White lead 9.21 Tin oxide 8.50

In preparing sanitaryrware with lead borate it is red in the usual manner, but upon observation it is found that the action of the glaze during the Y ring operation and the resultant product obtained is much more desirable than that obtained by the use of the well known boric acid method now in use, and which requires the preliminary making of a frit. The glaze material is more uniform in consistency and is easier to handle and to apply to the ware. It also has been demonstrated by its use that it will fuse at a much lower ternperature than most other glaze materials, and that in addition the fusion takes place without an initial cracking or blistering of the glazed material, but with an even uniform fusion. The character of the lead borate is such 'as to insure that it will melt before any such objectionable cracking occurs, and that it will be withdrawn from the fire in more satisfactory condition and with less possibility that the product will be rejected.

In the production of the lead borate it will be evident from the examination of the flow plan that the electrolyte may be maintained in continuous circulation so that ingredients which precipitate out due to the electrolytic and.' chemical reactions within the precipitation cell l may be replenished constantly, and so that the lead borate precipitate may be constantly drawn away and prepared for use.

It is to be understood that while the cell l0 is shown with only one anode and two cathodes, any number of each might be used. However, it is instead of frit, which would be normal procedure,

preferable to provide one more cathode than anode.

It will, of course, be understood that this material might be made by drawing off the entire quantity of electrolyte continuously and passing 5 it through the settling tank 25, after which a replenished electrolyte solution would be returned to the precipitation cell l0 and would be used to submerge the cathodesand the electrodes.

It will thus be seen that the invention here disclosed provides simple apparatus and a simple method for producing a glazing product, and for insuring that said product may be made uniformly and economically, and that the glazed ware obtained as a result of its ruse will be of high quality.

While I have shown the preferred form-of my invention, the method of making the same, and of using the product, it will be understood that Various changes might be made in the method, apparatus and proportions of parts by those skilled in the art without departing from the spirit of the invention as claimed.

Having thus described my invention, what I claim and desire to secure by Letters Patent is: 25 1. A method of producing lead borate within an electrolytic cell characterized by having a lead anode and metallic cathodes separated from each other by diaphragms through which electric current may flow, thereafter continuously introducing a boric acid containing electrolyte into the space occupied by the cathodes and continuously withdrawing the electrolyte from the space occupied by the anode, said Withdrawn electrolyte containing lead borate.

2. A method of producing lead borate Within an electrolytic cell characterized by having a lead anode and metallic cathodes separated from each other by diaphragms through which electric current may now, thereafter continuously introducing a boric acid containing electrolyte into the space occupied by the cathodes and continuously withdrawing the eletrolyte from the space occupied by the anode, said withdrawn electrolyte containing lead borate, and then separating the lead borate precipitate from the solution.

GUILIO E. SIEVERT. 

